Medial temporal lobe atrophy in Alzheimer's disease/mild cognitive impairment with depression

Objective:

Depression is common in patients with Alzheimer''s disease (AD) and mild cognitive impairment (MCI). Patients with depression have an earlier onset and rapid progression of cognitive decline. Medial temporal lobe atrophy (MTA) is common in AD and MCI, and some degree of atrophy is found in almost all patients. In the present study, an attempt was made to know if MTA is more common in patients with AD/MCI with depression than those without it.

Methods:

Patients reporting to the outpatient department of a neurology centre of a tertiary care hospital were recruited for the present study. After initial general physical and neurological examination, they were evaluated using National Institute of Neurological and Communicative Disorders and Stroke and Related Disorders Association criteria for diagnosis of AD. Clinical Dementia rating scale was used for the diagnosis of MCI. Cornell scale for depression in dementia (CSDD) was used.

Results:

We found 20 cases with depression as per CSDD out of a sample of 37 patients (male:female = 30:7). There were 26 patients with AD and 11 with MCI. The mean age of all patients was 72.33 ± 6.45 years. The mean mini mental status examination score was 19.00 ± 6.73. The mean time since diagnosis was 4.19 ± 3.26 years. The mean Scheltens visual rating scale score for right MTA was 2.08 ± 0.95 and was 2.05 ± 0.94 for the left. Both scores did not differ statistically when analyzed using paired t-test (p > 0.05). However, difference in those with depression (2.36 ± 0.95) from those without depression (1.60 ± 0.74) was significant (p < 0.05).

Conclusion:

MTA scores were higher in those with AD/MCI with depression than those without it.Depression¹ is common in patients with Alzheimer''s disease (AD) and mild cognitive impairment (MCI). Relationship between depression and cognitive decline is a complex one, and depression is both an aetiological risk factor² and comorbidity for dementia.³ Incidence and prevalence of depressive symptoms in MCI range from 15% in population-based studies to 44% in hospital-based studies.⁴ Likewise, up to two-thirds of patients with AD have been reported to have depression.⁵ Because in many studies, depression has been seen to be an early manifestation of AD, it has been suggested that it may represent a continuum⁴ from depression to MCI to AD (late-life depression → MCI → AD). Two recent meta-analyses have found that a history of depression approximately doubles an individual''s risk for subsequent dementia in general and AD in particular.⁶ Depression is known to be neurotoxic to medial temporal lobe structures and can contribute to their atrophy.^7–9 Atrophy is more so, when depression is severe or recurrent⁷ and medial temporal lobe atrophy (MTA) has a temporal association with depression.⁹ Continued treatment of depression has been shown to protect the hippocampus from the ill effects of depression.¹⁰ Although volumetric method could be a preferred mode of measuring the hippocampal volume in AD, qualitative rating of MTA is a good alternative.¹¹ Visual rating of the hippocampal volume^12–14 can be carried out using Scheltens et al¹⁵ rating scale that is based on the width of the choroid fissure, the width of the temporal horn and the height of hippocampal formation and is a quantitative scale.